This invention relates to a system for polishing articles such as semiconductor wafers, which is provided with an air exhaust system for creating a negative pressure in a housing of the polishing system.
During production of semiconductor devices, it is common to use a polishing system in which semiconductor wafers are subjected to a so-called chemical mechanical polishing (CMP) process to form a highly planarized surface for formation of an integrated circuit. During a chemical mechanical polishing process, semiconductor wafers are slidably engaged with and moved relative to a polishing surface, which surface is usually provided on an upper side of a turntable, and a chemical polishing liquid referred to as slurry is concurrently supplied onto the polishing surface.
Semiconductor devices are produced in a clean room, and a polishing system such as that mentioned above is installed in the clean room. During a polishing operation pollutants are generated, which may include: particles of polishing liquid scattered from a polishing surface; debris generated from a wafer or from a polishing surface; particles generated in driving assemblies for driving a turntable, and in cleaning machines for cleaning wafers which have been polished, and also in wafer transporting devices; and harmful gases emitted from a chemical cleaning liquid. It is necessary to prevent such pollutants from leaving a housing of the polishing system and entering the clean room. To this end, a pressure in the housing of the polishing system is kept lower than that in the clean room by exhausting or drawing out air from the housing.
However, since a volume of the housing of the polishing system is large, a large amount of energy is required to create a negative pressure in the housing relative to the clean room.
Accordingly, it is an object of the present invention to provide a polishing system with an air exhaust system which can efficiently exhaust or draw out air from a housing to create negative pressures in the housing, which are required to prevent pollutants, such as particles of a polishing liquid, from leaking from the housing.
According to one aspect of the present invention, there is provided a polishing system comprising:
a housing defining a chamber in which articles to be polished are subject to polishing and cleaning operations;
partition walls for dividing the chamber of the housing into a plurality of sections; and,
an air exhaust device comprising:
air exhaust conduits which are fluidly connected to sections in the housing to exhaust air from the sections;
valves for closing and opening respective ones of the air exhaust conduits, the conduits having inlet openings located in a vicinity of spaces where any air pollutant is generated in the sections in the housing; and,
a controller for independently controlling the valves to regulate air flows exhausted through the conduits.
In the polishing system of the present invention, since the inlet openings of the conduits are positioned in a vicinity of spaces where an air pollutant may be generated in the polishing system housing, any air pollutant can be efficiently discharged from the housing to prevent leakage of the air pollutant from the housing into space of a clean room, even in a case that a negative pressure employed in the housing is not as great as that employed in a housing of a conventional polishing system having an air exhaust system. Further, in the polishing system of the present invention, it is possible to independently control the valves. This makes it possible for the air exhaust system to perform an efficient and effective air exhaust operation, by conducting such an operation on a basis of various conditions such as an air pressure in various sections in the housing of the polishing system, a degree of air pollutants in the sections, and the like.